The invention relates to a textile yarn which has been coated with a size coating to give the yarn better weavability in the subsequent process of weaving fabric on a loom. Typically, the warp yarns are subjected to a sizing process on a textile slashing machine prior to being woven whereupon a protective coat of size is applied to the individual threads or fibers of the yarn to cement the threads together and prevent chaffing and breaking during weaving.
In the conventional sizing process, the warp yarn ends are passed under an immersion roll and totally immersed in a sizing solution in a slasher box where the individual fibers in each warp yarn end absorb the sizing solution. The yarns are then passed to the nip of a pair of pressure rolls where the excess sizing is squeezed out of the yarn and rolled back into the sizing box. It has also been known to pass the warp yarns directly to the nip of the rollers where the sizing fluid is carried by a bottom application roll and pressure exerted by an upper pressure roll in contact with the application roll squeezes the surplus of sizing liquid out of the yarn and retains the surplus at the nip whereupon it goes back to the tank (U.S. Pat. No. 1,822,425). In both cases, however, the object is to thoroughly soak and encapsulate the warp yarn ends with the sizing solution.
Since the primary consideration in applying a size coating to a warp yarn is to eliminate warp breaks during weaving, it has always been thought that total soaking and encapsulation of all the fibers in the yarn to increase the fiber-to-fiber cementing was required to provide sufficient tensile strength and prevent warp breaks during weaving. The use of two size boxes on a slasher machine has even been proposed where the yarn is passed successively through each box to pick up a heavier film coating or greater quantity of size to hold the yarn fiber bundle together.
However, the problem occurs that considerable amounts of energy are required to dry the yarn since the sizing must be in solution with a large part of water in order to soak the yarn bundle. The water must then be subsequently squeezed and dried out of the yarn. In addition, when the yarn is encapsulated and soaked, the yarn picks up sizing in proportion to its absorption capacity which means that the thicker yarn sections pick up more size than the thin sections. This results in the yarn remaining at ununiform strength since the thick sections retain more size and strength over the thin sections. During weaving, the warp yarn breaks at the thin section.
Accordingly, an important object of the present invention is to provide a sized yarn which provides good weavability but requires less energy to produce.
Yet another important object of the present invention is to provide a sized yarn having an increased tensile strength to reduce the number of warp breaks during weaving and hence increase the production of woven fabric.
Yet another important object of the present invention is to provide a sized yarn which has a more nearly uniform tensile strength such that the weak spots are diminished and the number of warp breaks reduced.